The intake silencer restricts airflow by a negligible amount. You may see a minor power gain but for most users it is increased throttle response due to a stiffer intake system and increased volume that makes the butt dyno happy. The silencer effectivly acts as a holding space for vibration and static air. When the turbo spools and the intake (pre turbo) is under vacuum you want to be sucking in fresh air rather than static air warmed by the engine bay. the limiting factor on the stock intake is really the panel filter, and even then its good for 350 whp as long as you are keeping your stock panel then there is no reason to re-tune.

TLDR No Pro-tune required for silencer delete but pro-tunes are always recommended.